The present invention generally concerns flow control valves, and more specifically, but not exclusively, concerns a flow control valve that is able to regulate fluid flow and temperature during both low and high flow conditions.
Comfort and safety are always a concern when designing water control systems for showers or baths. One typical problem that arises during showering (or taking a bath) is the shower's inability to maintain a constant temperature due to variations in supply pressure or in coming water temperature. Many have experienced the unpleasant effects of momentarily being sprayed by frigid water in a shower due to the operation of a dishwasher or washing machine. Even worse, serious burns and other injuries can result when the supply of cold is reduced during the shower, such as when a toilet is flushed or a lawn sprinkler system is activated. It is therefore desirable to maintain a proper flow balance between the hot and cold water in the shower, or even in the bath, so as to prevent scalding or cold water shock.
Maintaining a consistent flow rate from showerheads is also a concern. Under current energy regulations, it has been mandated that home showerheads are limited to a maximum flow rate of 2.5 gallons per minute. Recently, it has become popular for showers to incorporate multiple spray heads or showerheads so that the individual can be sprayed from multiple directions, thereby providing a more pleasant overall shower experience. To further enhance the experience, individual sprays can be turned on and off, either automatically or manually, to create a varying spray pattern. High water flow demand conditions can occur when the water is sprayed from multiple showerheads at the same time and/or when water flows from the bathtub spout, which can tax the control valve supplying water to the showerheads. If the water flow during high demand conditions is insufficient to supply water to all of the showerheads, the water can trickle from the showerheads, which is unsatisfactory in most circumstances. In contrast if the shower/bath valve is sized correctly to provide sufficient flow for these high demand situations then during low demand situations, such as a single showerhead, the valve is effectively “oversized” and precise flow or temperature control is difficult or impossible. In addition, when low demand water flow conditions occur, the spray of water from the showerhead can become unpleasantly hard due to high backpressure. Further complicating matters, flow conditions can rapidly fluctuate when the shower changes between a single showerhead spray mode to a multiple showerhead spray mode. If not properly regulated when switching between modes, the water can flow from the showerheads at an undesirable rate and/or the water temperature can fluctuate. For instance, switching from a single spray mode to a multiple spray mode can result in the water merely trickling showerheads, instead providing an invigorating spray. In a typical multiple-head shower installations, the water for all of the showerheads (and bathtub spout, if so equipped) is fed through a single control valve assembly that regulates the flow of water to the shower or tub. However, conventional valves are usually unable to accurately and automatically control the desired water flow rate and water temperature under both low and high flow demand conditions. Therefore, there is a need for improvement in this field.